1. Field of the Invention
The present invention relates to a fuse. More particularly, the present invention relates to a blade-type fuse in which a fuse element, having a fusible portion provided between a pair of parallel flat-plate terminal portions, is mounted within an insulating housing.
The present application is based on Japanese Patent Application No. 2000-143952, which is incorporated herein by reference.
2. Description of the Related Art
A related fuse 50, shown in FIG. 7, is a blade-type fuse in which a fuse element 56 is formed by providing a fusible portion 52 between a pair of parallel flat-plate metal terminals (hereinafter referred to as xe2x80x9cflat-plate terminalsxe2x80x9d) 51 and 51, and a proximal end portion of this fuse element 56 (at which the fusible portion 52 is provided) is received in an insulating housing 53.
Each of the flat-plate terminals 51 includes a terminal body portion 54, received in the insulating housing 53, and a tab terminal portion 55 considerably projecting outwardly (downwardly in FIG. 7) from the insulating housing 53.
The fusible portion 52, having a predetermined cross-sectional area, extends between opposed inner side edges 54a and 54a of the flat-plate terminals 51 and 51.
As shown in FIG. 8, the fuse 50 is mounted in a fuse mounting portion 60 such as a fuse box, and the tab terminal portions 55 are fixedly gripped by mating terminals 61 of the fuse mounting portion 60, respectively, and therefore are electrically connected to these mating terminals 61, respectively.
As shown in FIG. 9, the mating terminal 61 is, for example, a so-called tuning fork-type connection terminal comprising a terminal piece portion formed at one end of a bus bar, and a distal end portion of this terminal piece portion is bifurcated by a slot 61b of a U-shaped contour extending in a direction of extending of the terminal piece portion, and upper ends of this bifurcated distal end portion are bulged inwardly toward each other to form a pair of gripping portions 6la and 61a, respectively.
However, if the tab terminal portions 55 (the lower portions of the flat-plate terminals 51 in FIG. 9) are merely supported by and fixed to the mating terminals 61, respectively, when the fuse 50 is mounted in the fuse mounting portion 60, the balance of supporting of the fuse in the fuse mounting portion 60 is not good.
Therefore, fuse guide walls 62, which support the insulating housing 53, and serve to guide the insertion of the fuse during the mounting operation and also to prevent the deflection and the like of the fuse 50 in its mounted condition, must be provided at the fuse mounting portion 60 as shown in FIG. 8.
The fuse mounting portion 60 has an insulating wall 63 for preventing a leakage of current between the tab terminal portions 55 and 55 of the mounted fuse 50. This insulating wall 63 need to have a sufficient height in the direction of the length of the tab terminal portions 55 and 55 considerably projecting outwardly from the insulating housing 53. An upper end of the insulating wall 63 is abutted against a lower end edge of the insulating housing 53, thereby positioning the fuse 50 relative to the fuse mounting portion 60.
Therefore, the height of the fuse mounting portion 60 in the fuse-mounting direction is increased because of the provision of the fuse guide walls 62 and the insulating wall 63, and this has invited a problem that the fuse box or the like is increased in size. In addition, the fuse guide walls 62 need to have a high molding precision so as to prevent the deflection of the fuse 50.
And besides, for mounting the fuse 50 in the fuse mounting portion 60, each tab terminal portion 55 must be gripped by the gripping portions 61a and 61a of the mating terminal 61 disposed in a deep bottom portion enclosed by the fuse guide wall 62 and the insulating wall 63, and therefore the efficiency of the inserting operation was not good.
Furthermore, the tab terminal portions 55 of the flat-plate terminals 51 of the fuse element 56 considerably project outwardly from the insulating housing 53, and therefore there have been encountered problems that upon contact of a plurality of fuses 50 with each other during transport or others, the tab terminal portions 55 of these fuses are damaged, and that the fusible portion 52 is liable to be deformed or broken by an external force applied to the tab terminal portions 55 upon contact with other member.
Therefore, it is an object of the present invention to solve the above problems, and more specifically to provide a good fuse in which a balance of supporting of the fuse in a fuse mounting portion is enhanced, and the fuse mounting portion can be formed into a small size, and the efficiency of an inserting operation can be enhanced, and besides the deformation and breakage of a fusible portion by an external force can be prevented.
To achieve the above object, according to the first aspect of the present invention, there is provided a fuse which comprises a fuse element including a pair of parallel flat-plate terminal portions, and a fusible portion formed between inner side edges of the flat-plate terminal portions; and an insulating housing covering the fusible portion and upper end edges and the inner side edges of the flat-plate terminal portions, wherein a middle portion of each of the flat-plate terminal portions in a mounting direction of the fuse can be fixedly gripped between gripping portions of each mating terminal of a fuse mounting portion in a plate thickness direction of the flat-plate terminal portions, so that the flat-plate terminal portions are electrically connected respectively to the mating terminals.
To achieve the above object, according to the second aspect of the present invention, there may be provided a fuse which comprises a fuse element including a pair of parallel flat-plate terminal portions, and a fusible portion formed between inner side edges of the flat-plate terminal portions; and an insulating housing covering the fusible portion and upper end edges and the inner side edges of the flat-plate terminal portions, wherein middle portions of the flat-plate terminal portions, that are respectively located at lateral positions relative to the fusible portion, can be fixedly gripped between gripping portions of mating terminals of a fuse mounting portion in a plate thickness direction of the flat-plate terminal portions.
In the above construction, the fuse element, in which the inner side edges and upper end edges of the flat-plate terminal portions and the fusible portion are covered with the insulating housing, does not have any tab terminal portions considerably projecting outwardly from the insulating housing as in the related fuse.
Therefore, even when a plurality of fuses are brought into contact with each other during transport or others, the fuse elements, each having no tab terminal portion projecting from the insulating housing, are not liable to be brought into contact with each other, and besides are not liable to receive an external force which would be produced upon contact with other member. Therefore, the flat-plate terminal portions are prevented from damage, and also an external force is prevented from being applied to the fusible portion, thus preventing the fusible portion from being deformed or broken.
The middle portion of each flat-plate terminal portion of the fuse element in the mounting direction is fixedly gripped by the mating terminal in the direction of the plate thickness of the flat-plate terminal portion. Therefore, as compared with the related fuse in which the tab portions, projecting from the insulating housing, are adapted to be fixedly supported, the balance of supporting of the fuse in the fuse mounting portion is better, and the deflection of the fuse in its mounted condition is suppressed, and besides the overall height of the fuse can be reduced.
Therefore, fuse guide walls of the fuse mounting portion do not need to have a high molding precision so as to prevent the deflection and the like of the fuse, and also the height of the fuse guide walls can be reduced. Therefore, the fuse mounting portion can be formed into a small size, and besides the efficiency of the fuse-inserting operation can be enhanced.
In the case where the middle portion of each flat-plate terminal portion, that is located at a lateral position relative to the fusible portion, is adapted to be fixedly gripped by the mating terminal of the fuse mounting portion in the direction of the plate thickness of the flat-plate terminal portion, the substantially central portion of each flat-plate terminal portion in the mounting direction is fixedly gripped by the mating terminal in the direction of the plate thickness of the flat-plate terminal portion, and by doing so, the balance of supporting of the fuse in the fuse mounting portion is made better.
Further, according to the third aspect of the present invention, it is preferable that the insulating housing includes positioning abutment portions which abut respectively against the mating terminals so as to position the fuse when the fuse is mounted to the fuse mounting portion. In this case, the fuse is directly positioned relative to the mating terminals, and therefore the fuse does not need to be positioned relative to the insulating wall and others of the fuse mounting portion, so that the accurate positioning can be effected regardless of the molding precision of the fuse mounting portion.
Further, according to the fourth aspect of the present invention, it is preferable that the insulating housing covers outer side edges of the flat-plate terminal portions. With this construction, the exposure of the fuse element is reduced to the minimum of the required amount, and therefore the damage prevention and the protection of the fusible portion can be achieved more positively.
Further, according to the fifth aspect of the present invention, it is preferable that the insulating housing comprises a pair of housing members which are integrally connected together in a manner to hold the fuse element therebetween in the plate thickness direction of the flat-plate terminal portions, and a pair of large and small pins are formed on and project from an inner surface of each of the housing members, and wherein the pins pass respectively through corresponding through holes, formed through the flat-plate terminal portions, and then are fitted respectively in fitting holes formed in the inner surface of the housing member to which the pins are opposed. With this construction, even if the outer side edges and lower end edges of the flat-plate terminal portions receive an external force due to contact with another member, the external force is not directly applied to the fusible portion easily because the flat-plate terminal portions are penetrated and supported by the pins of each of the housing members.